In machines for inserting sheets into envelopes, an envelope unstacker at the outlet from a magazine of envelopes takes envelopes one by one from the magazine. A transfer mechanism transfers the separated envelopes to an insertion station for inserting sheets into said envelopes.
At the insertion station successive envelopes are stopped and held open. The sheets to be put into the envelopes, which may be in the form of single sheets or in the form of bundles of sheets are delivered successively to the machine after being appropriately folded in a folding machine and optionally made up into bundles either before or after folding.
A tray which is movable back and forth and which is referred to as a "carriage" is used for transferring successive sheets that it receives and for inserting them into respective envelopes at the insertion station. The carriage engages itself together with the sheet it is carrying into the open envelope present at the insertion station, and it then withdraws from the envelope leaving the sheet behind. An ejection device serves to eject and remove filled envelopes in order to allow a new insertion to take place.
In such a machine, the number of different devices contained therein give rise to a machine which is excessively bulky, in particular when the machine is intended for use as an item of office machinery, or the like. The mechanisms which control these various devices synchronously further increase the complexity and the bulk of the machine. In order to meet current requirements, these control mechanisms must be capable of operating at high insertion rates with the various devices operating with a high degree of reliability.
The object of the present invention is to satisfy these needs with a machine which is compact, and which is capable of operating reliably at a high throughput.